More than 400 Ukrainian soldiers have crossed the border into Russia, a Russian border-security official told Fox News.

Russia and Ukraine have provided conflicting accounts as to why the soldiers have crossed the border: The Russian official claimed that the Ukrainian soldiers deserted the Kiev government and that Russia has offered safe passage, while a Ukrainian military official told Fox that attacks from separatists forced the soldiers into Russia.

The Ukrainian official said that the troops had come under a sustained attack from separatist forces, for over four hours, and were forced to divide up after they ran out of ammunition.